Human trophoblast invasion and spiral artery transformation - The role of PECAM-1 in normal pregnancy, preeclampsia, and fetal growth restriction

During early human pregnancy extravillous cytotrophoblasts invade the uteru s and spiral arteries transforming them into large vessels of low resistanc e, Failure of trophoblast invasion and spiral artery transformation occurs in preeclampsia and fetal growth restriction (FGR); these processes are not well understood. Recent studies have suggested that cytotrophoblasts that invade spiral arteries mimic the endothelial cells they replace and express PECAM-1. It was also reported that in preeclampsia, cytotrophoblasts fail to express PECAM-1 and that failure to express endothelial cell adhesion mo lecules may account for failed trophoblast invasion. Despite the possible i mportance of adhesion molecules in trophoblast invasion, no study has syste matically investigated the expression of PECAM-1 in the placental bed throu ghout the period of invasion, particularly in the myometrial segments where the key failure occurs. There are no studies on PECAM-1 expression in the placental bed in FGR, We have examined the expression of PECAM-1 in placent al bed biopsies and placentas from 8 to 19 weeks Of gestation and in the pl acenta and placental bed in the third trimester in cases of preeclampsia, F GR, and control pregnancies. PECAM-1 was expressed on endothelium of vessel s in the placenta and placental bed but not by villous or extravillous trop hoblasts in normal or pathological samples. These findings do not support a role for PECAM-1 in normal invasion or in the pathophysiology of preeclamp sia or FGR.